CVE-2002-0426 in BEFVP41
Summary
by MITRE
VPN Server module in Linksys EtherFast BEFVP41 Cable/DSL VPN Router before 1.40.1 reduces the key lengths for keys that are supplied via manual key entry, which makes it easier for attackers to crack the keys.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability identified as CVE-2002-0426 affects the VPN Server module in Linksys EtherFast BEFVP41 Cable/DSL VPN Router devices running firmware versions prior to 1.40.1. This represents a significant cryptographic weakness that directly impacts the security of VPN communications. The flaw specifically targets the manual key entry functionality used for configuring VPN connections, creating a pathway for adversaries to compromise the encryption mechanisms that protect network traffic. The vulnerability falls under the category of cryptographic weakness and directly relates to improper implementation of security protocols that should ensure robust key management and encryption strength.
The technical implementation flaw stems from the router's VPN server module reducing key lengths for manually entered keys. This reduction in key entropy significantly weakens the cryptographic strength of the VPN connections, making them more susceptible to brute force attacks and cryptographic analysis. The vulnerability operates at the protocol level where user-supplied keys are processed, and the system fails to maintain adequate key length requirements that would normally be expected for secure VPN implementations. This weakness creates a predictable cryptographic environment where attackers can more efficiently determine the correct key through reduced computational requirements. The issue demonstrates poor adherence to cryptographic best practices and represents a failure in key validation and enforcement mechanisms.
The operational impact of this vulnerability extends beyond simple encryption weakness to encompass potential network compromise and unauthorized access to sensitive data. Attackers who can successfully crack the reduced-length keys gain access to VPN sessions and can potentially intercept, modify, or redirect network traffic passing through the compromised router. This vulnerability particularly affects organizations relying on VPN connectivity for remote access, as it undermines the fundamental security assumptions of encrypted communications. The reduced key strength means that network administrators who depend on VPN for secure remote access are exposed to increased risk of data breaches, man-in-the-middle attacks, and unauthorized network penetration. The vulnerability affects the confidentiality and integrity of all data transmitted through the compromised VPN connections, potentially exposing sensitive corporate or personal information.
Mitigation strategies for this vulnerability require immediate firmware updates to version 1.40.1 or later, which address the key length reduction issue in the VPN server module. Network administrators should also implement additional security controls such as multi-factor authentication for VPN access, network segmentation to limit exposure, and regular monitoring for unauthorized VPN connections. The vulnerability demonstrates the importance of proper key management and cryptographic implementation, aligning with security standards such as those outlined in the NIST SP 800-57 for key management practices and the CWE-327 weakness category for broken cryptographic implementations. Organizations should also consider implementing network access control measures and regular security assessments to identify similar vulnerabilities in their network infrastructure. The ATT&CK framework categorizes this vulnerability under T1566 for credential access and T1041 for data compression, as compromised VPN credentials can lead to further exploitation and data exfiltration activities.